I have been looking at those pics for a long time now and there's somthing that confuses me..... but I think I know what happened...
That driver had to be going VERY quick , or been very unlucky at the point where they hit the gaurdrail....I looked at the ends of ours here and there are STEEL pilars at the front, not wood, bracing them to the ground so the likelyhood of starting at the front isn't possible. Also, the fronts are bent and would not have cut into the vehicle so cleanly.
My scenario.....(this is not fact....just a guess)
The driver wasn't paying attention, or was forced off the road into the far right lane(or the left lane exiting)...possible swtching to quickly after missing an exit. As the driver swerved over, lost control and hit the guardrail, however, hit it RIGHT at the wood pilar, and start of a new section. If you look at the 3rd pic down you can see the rivets are on the OUTSIDE, so that one overlaps. thus the passenger side went through, and the drivers side caught the beginning of a new piece. shattered the wooded rail, thus causing the V break in the front just left of the rail, and continued it's path stopping at the next pillar.
I'm not sure that the driver was impaled though. You can't see blood anwhere else on the guardrail, and the blood goes left to right, not back, meaning there was no force back and that was at that area, possibly the drivers scalp bleeding.
Sorry, if that sounds disgusting....just trying to figure out what/how that happened